Preapplied plastic film adhesive composition

ABSTRACT

This invention relates to a preapplied adhesive coating which can be deposited onto parts (e.g., nuts and bolts, slip-fitted tubing, or flanges), and left for long periods of time prior to use. The preapplied adhesive coating is dry to the touch, yet when the parts are assembled, the composition will cure between the parts, sealing and bonding them. The composition is comprised of a polymerizable monomer, a binder system, an initiator, and an accelerator of polymerization. The binder system is comprised of a copolymer of an anhydride and a compound selected from the group consisting of arylenes, alkylenes, alkarylenes, aralkylenes, alkoxyalkylenes, alkoxyarylenes, aryloxyalkylenes, and aryloxyarylenes. 
     This invention also concerns an article, particularly threaded fasteners and the like, which is coated with the preapplied adhesive coating.

BACKGROUND OF THE INVENTION

The concept of preapplied adhesives has long been recognized as adesirable object and numerous attempts have been made to provide suchadhesives. For example, attempts have been made to encapsulate two-partadhesives, such as epoxides, and to apply them to parts prior toassembly. While this has permitted pre-application of adhesives toparts, totally acceptable results have not been achieved. Theencapsulation process is quite cumbersome and the attachment of capsulespresents certain inherent problems, such as risk of loss of the capsulesfrom the surface during storage or shipment. Also, mistreatment prior touse can lead to loss of adhesive due to premature rupturing of thecapsules.

One attempt to solve the problems of preapplied encapsulated adhesiveswas to affix a coating or sheet material which does not migrate or flowoff parts prior to the time of assembly, e.g., during normal storage andshipment. Adhesives of this sort are disclosed in U.S. Pat. Nos.3,547,851 and 3,625,875. These patents disclose non-flowable anaerobicsheets or coatings which can be preapplied to a part and which willprovide a convenient means of bonding to a mating surface. Compositionsof these references are particularly useful on threaded fasteners, wherethe adhesive provides increased holding power and resistance toloosening of the mating surface, e.g., as in the case of nuts wound onbolts.

It is known in the prior art to use a polymerizable acrylate ester, aperoxy initiator, an accelerator and an aqueous system comprised ofpolyvinyl alcohol (see U.S. Pat. Nos. 3,814,156 and 3,489,599). Thispreapplied coating, however, does not always produce adequate adhesionto the substrate and sometimes peels easily or flakes off the part towhich it has been preapplied. The results is lower bond strengths whenthe coated part is mated with another part. Additionally, these priorart compositions tend to be surface-sensitive and peeling is especiallylikely on inactive surfaces such as zinc, cadmium, and dichromates. As adirect result of such failure of the preapplied films of these adhesivescompositions to adhere adequately to substrates, only some of thecomposition would be left to provide adhesion to a mated part, whichthen results in low torque values between a nut and bolt which have beencoated with the prior art preapplied compositions. A further problemencountered in the prior art compositions was the interference of thebinding system, in most instances polyvinyl alcohol, with the cure ofthe monomer.

Accordingly, there is a need for a stable adhesive composition which canbe prepared and preapplied conveniently to a variety of metallic as wellas non-metallic surfaces prior to the time of assembly, which willremain on the parts during normal storage and shipment, and which willcure upon mating with another part thereby imparting an effective andimproved seal or bond. It is also desirable to have such a compositionwhich is resistant to heat aging, which has an extended pot-life, andwhich has a binder system which allows for proper deposition andadherence of the preapplied adhesive composition.

SUMMARY OF THE INVENTION

This invention relates to adhesive compositions which are useful aspreapplied coatings, sealants, or films. The composition can bedeposited on a substrate by any of the methods known in the art, such astumbling, by hand, or application machines. The coated objects can thenbe shipped or stored for substantial periods of time prior to cure.Handling and shipping of parts coated with the preapplied composition isfacilitated because the coatings are dry to the touch. Additionally, theinstant compositions resist the peeling often encountered during storageor shipment of articles coated with the prior art compositions. Theinstant compositions are most useful as films applied to threadedarticles such as fasteners, but other uses such as gasketing or bondingare contemplated. This invention also concerns an article coated with apreapplied adhesive composition, said preapplied adhesive compositionbeing dry to the touch upon evaporation of the solvent (water) but whichwhen crushed or ground by a mating surface, cures to a strong bond.

The preapplied adhesive compositions of this invention may be one- ortwo-part systems, the two-part being preferred. These compositionscomprise: (a) a polymerizable monomer; (b) an initiator; and (c) anaccelerator of polymerization; and (d) a binder, wherein the binder is acopolymer of the formula: ##STR1## where Z is selected from the groupconsisting of H; C₁₋₁₀ alkyl, alkoxy, alkylene, cycloalkyl; cyano andhalo; m is an integer from about 100-1,000; n is greater than 0 but lessthan 1; and p is 1-n. The specific binders of the instant invention, incombination with the other essential ingredients, give greatly improvedpreapplied compositions, which resist peeling and allow for strongerbonds upon cure of the adhesive. In the two-part embodiment, thefree-radical initiator would be encapsulated in a suitable shell andwould constitute one part, while the remaining essential ingredients,the monomer, binder, and accelerator, would constitute the second part.The microcapsule shell wall is preferably composed of a ureaformaldehyde composition. The initiator-filled microcapsule would beadded to the first part containing the monomer, accelerator and binderprior to deposition on a part.

DETAILED DESCRIPTION OF THE INVENTION AND ITS PREFERRED EMBODIMENTS

The polymerizable monomers useful in this invention include a widevariety of compounds which undergo polymerization reactions. Vinylcompounds, unsaturated polyesters, poly-and mono-functional acrylateesters are among the general classes of compounds which are contemplatedfor use. One preferred class of polymerizable monomers is the poly- andmono-functional acrylate and methacrylate esters of the generalformulas:

    CH.sub.2 ═C(R).COOR.sup.1                              (I)

where R is H, CH₃, C₂ H₅ or Cl, and R¹ is C₁₋₈ mono-or bicycloalkyl, a 3to 8-membered heterocyclic radical with a maximum of 2 oxygen atoms inthe ring, H, alkyl, hydroxyalkyl or aminoalkyl where the alkyl portionis C₁₋₈ straight or branched carbon atom chain; and ##STR2## where R² isH, C₁₋₄ alkyl or hydroxyalkyl or --CH₂ --OO═C--C(R¹)C═CH₂ ; R³ is H,halogen or C₁₋₄ alkyl; R⁴ is H, OH or --OO═C--C(R¹)═CH₂ ; m is aninteger from 1 to 8; n is an integer from 1 to 20, and p is 0 or 1; R¹is C₁₋₈ mono-or bicycloalkyl, a 3 to 8-membered heterocyclic radicalwith a maximum of 2 oxygen atoms in the ring, H, alkyl, hydroxyalkyl oraminoalkyl where the alkyl portion is C₁₋₈ straight or branched carbonatom chain.

Other preferred acrylate ester monomers are those selected from theclass consisting of urethane acrylates having the general formula:

    (CH.sub.2 ═CR.sup.5.CO.O.R.sup.6.O.CO.NH--).sub.2 R.sup.7(III)

wherein R⁵ is H, CH₃, C₂ H₅ or Cl; R⁶ is (i) a C₁₋₈ hydroxyalkylene oraminoalkylene group, (ii) a C₁₋₆ alkylamino-C₁₋₈ alkylene, ahydroxyphenylene, aminophenylene, hydroxynaphthylene or aminonaphthyleneoptionally substituted by a C₁₋₃ alkyl, C₁₋₃ alkylamino or di-C₁₋₃alkylamino group; and R⁷ is C₂₋₂₀ alkylene, alkenylene or cycloalkylene,C₆₋₄₀ arylene, alkarylene, aralkarylene, alkyloxyalkylene oraryloxyarylene optionally substituted by 1-4 halogen atoms or by 1-3amino or mono- or di-C₁₋₃ alkylamino or C₁₋₃ alkoxy groups; or saidacrylates having the general formula:

    (CH.sub.2 ═CR.sup.5.CO.O.R.sup.6.O.CO.NH.R.sup.7.NH.CO.X--).sub.n R.sup.8                                                   (IV)

wherein R⁵, R⁶, and R⁷ have the meanings given above; R⁸ is thenon-functional residue of a polyamine or a polhydric alcohol having atleast n primary or secondary amino or hydroxy groups respectively; X isO or NR⁹ where R⁹ is H or a C₁₋₇ alkyl group; and n is an integer from 2to 20.

Among the specific monofunctional polymerizable acrylate ester monomerspreferred, and which correspond to the above formula I, arehydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, methylmethacrylate, tetrahydrofurfuryl methacrylate, cyclohexyl methacrylate,2-aminopropyl methacrylate and the corresponding acrylates.

Specific polyfunctional monomers which are preferred, and whichcorrespond to formula II above, are polyethyleneglycol dimethacrylateand dipropylene glycol dimethacrylate.

Other preferred polymerizable acrylate ester monomers useful in theinstant invention are selected from the class consisting of theacrylate, methacrylate and glycidyl methacrylate esters of Bisphenol A.The most preferred among all of the free-radical polymerizable monomersmentioned is ethoxylated Bisphenol-A-dimethacrylate.

Mixtures or copolymers of any of the above-mentioned free-radicalpolymerizable monomers can be employed.

Polymerizable vinyl monomers represented by the general formula:

    R.sup.10 --CH═CH--R.sup.10

where R¹⁰ is alkyl, aryl, alkaryl, aralkyl, alkoxy, alkylene, aryloxy,aryloxyalky, alkoxyaryl, or aralkylene, --OO═C--R¹, where R¹ is definedabove, can also be effectively employed in the instant composition.

Copolymers or mixtures of monomers disclosed herein with othercompatible monomers are also contemplated.

The binders of the instant compositions are generally copolymers formedby the reaction of an anhydride and a compound selected from the groupconsisting of arylenes, alkylenes, alkoxylenes, alkarylenes,aralkylenes, alkoxyalkylenes, alkoxyarylenes, aryloxyalkylenes andaryloxyarylenes.

The anhydrides useful in forming the copolymeric binders are of theformulas: ##STR3##

The copolymeric binders formed from this reaction are represented by thefollowing formulas: ##STR4## where Z is selected from the groupconsisting of H; C₁₋₁₀ alkyl, alkoxy, alkylene, cycloalkyl; cyano andhalo; m is an integer from about 100-1,000; n is greater than 0 but lessthan 1; and p is 1-n.

The most preferred copolymeric binder is ethylene maleic anhydride. Thisparticular copolymer is available under the trade names of EMA-21,EMA-31, EMA-61, EMA-91, and EMA-1103, among others, and manufactured byMonsanto Company, St. Louis, Missouri. The maleic anhydride copolymersare synthesized by reacting one mole of ethylene with one mole of maleicanhydride. According to Monsanto literature, linear as well ascross-linked grades of the resulting anhydride copolymers are availablein a range of molecular weights, each of which has particularproperties. For purposes of this invention, it has been found mostuseful to use a combination of linear and cross-linked grades, e.g.,EMA-31 and EMA-91, respectively. The linear grades of the copolymer aregenerally very soluble in water, while the highly cross-linked gradesbecome increasingly less soluble proportional to their molecular weightand typically form water gels. These copolymers are highly effective ataltering the viscosity of water-based products whose final formulationmay be a slurry, dispersion, or stable suspension. The preferredphysical form of the instant invention is a dispersion of the monomer inthe binder. Temperature and the addition of agents which affect pH canalso be effective in controlling the viscosity of the solution. Ofparticular importance is the fact that the instant binders form stablesuspensions or dispersions, keeping the monomer and binder fromseparating into their respective continuous phases for long periods oftime at elevated temperatures.

Without wishing to be bound by any one theory, it is believed that theethylene maleic anhydride binder helps to account for the improvement inthe instant preapplied adhesive compositions and contributes to theadhesion of the preapplied film to a substrate through hydrolysis of theanhydride ring and subsequent exposure of its polar groups to thesubstrate surface. The instant compositions exhibit little or nopeeling, once preapplied, and excellent adhesive strengths when matedwith other parts.

The ratio of pendent polar groups to the total number of carbons in thebackbone chain, as well as the relative position of these polar groupsto each other and to a substrate surface, are believed to have an effecton the adhesion of the films and coatings to substrates, although theinvolved relationships have not been determined. Selection ofappropriate ratios is considered to be a matter of routineexperimentation within the skill of the art.

It is recommended that the pH of the instant adhesive compositions bekept in the general range of about 2 to about 12. The preferred range isabout 4 to about 6. Adjustments to pH, particularly following hydrolysisof the anhydride ring, can be made by incorporating an effective amountof an organic or inorganic base. The instant adhesive compositions haveoptimum strengths on inactive surfaces, such as dichromates, cadmium andzinc, when the pH is about 4 to about 6. Two bases which areparticularly useful in controlling pH and which do not interfere withthe polymerization of the monomers are NH₄ OH and NaOH. The addition ofa base to obtain a pH between about 4 to about 6 should be done formaximum adhesion of the preapplied composition to a substrate, and it iswithin the scope of the persons skilled in the art to do so.

The basic purpose of the binder is to support the monomer and otheringredients, allowing for easy deposition on a part. It is essentialthat the binder not interfere with the polymerization of the monomer.The binder should be at least partially soluble in water and preferablyreadily soluble. However, inasmuch as some binders of the instantinvention will be more soluble than others, it is most useful andrecommended that a combination of binders be used, one of which is alinear copolymer and the other a cross-linked copolymer. If such acombination is employed, it is preferred that they be used in a ratio ofabout 5 to about 1, more preferably about 2 to about 1, linear tocross-linked, respectively, and that they be of the same essentialstarting materials. Thus, for example, linear and crosslinked grades ofethylene maleic anhydride copolymers may be used.

Generally, the monomer, along with the accelerator of polymerization, isadded to the binder which is at least partially in aqueous solution. Themonomer, together with the accelerator are dispersed or suspended intosmall droplets in the binder.

The monomer droplet size must not be too small as to cause poor adhesionand subsequent peeling, not too big as to be unable to wet the substratesurfaces. Generally, the dispersed monomer droplets are in the sizerange of about 50 to about 500 microns and preferably about 100 to about200 microns.

The upper limit of the monomer loading is determined by the point atwhich the phase of monomer dispersed in binder becomes reversed; thatis, the point at which the amount of monomer is so great as to cause thebinder to be dispersed in the monomer. At this upper limit, the monomerwould no longer be supported by the binder and would run off parts whenapplied. Thus, the upper limit of monomer to be used is dependent, tosome degree, on the specific monomer chosen. Generally, the upper limitof the amount of monomer would be about 35% to about 40% by weight. Theviscosity of the adhesive composition as a whole must be within a rangewhich allows easy deposition on parts through any of the known methods,e.g., tumbling, hand application, mechanical applicators, and whichprevents the composition from migrating off parts.

Upon application of the adhesive composition to a part, the water in thecomposition is allowed to evaporate either at room temperature or underheat supplied by any of the conventional methods such as induction heat,convection heat, radiant heat, infra-red, or microwave. The resultantpreapplied coating or film is dry to the touch once the water has beenevaporated.

Generally, the Brookfield viscosity ratio range of the adhesive isbetween about 60,000 and about 100,000 at 2 RPM's and 18,000-36,000 at20 RPM's, using a Brookfield RVF viscometer, a #6 spindle and measuredat a temperature of 25° C. The binder, including its water solvent, isgenerally present in the instant compositions in the amount of about 60%to about 90% by weight of the composition, and preferably about 60% toabout 70% by weight.

The invention will be further described in terms of free-radicalpolymerization. Initiators of free-radical polymerization useful in theinstant composition include peroxides, hydroperoxides, peresters, andperacids. Peroxides are preferred and benzoyl peroxide is the mostpreferred. Such initiators are generally present in the adhesivecomposition in the amounts of about 0.1% to about 10% by weight of themonomer, and preferably about 0.1% to about 2.0% by weight. Aspreviously mentioned, a two-part adhesive composition is preferred, onepart composing an encapsulated initiator which is added to thedispersion prior to application of the adhesive composition to a part.

Commonly known accelerators of polymerization include amines andsulfimides. Tertiary amines, such as N,N-dimethylparatoluidine, andsulfimides such as 3-oxo-2,3-dihydrobenz-[d]isothiazole-1,1-dioxide,commonly known as saccharin, are particularly useful. However, the mostpreferred accelerators are organomettalic compounds, preferablyorganometallic polymers containing a metallocene moiety such as aferrocene moeity. Suitable metallocenes in related compositions aredisclosed more fully in U.S. Pat. No. 3,855,040. These metallocenecompounds, as well as the accelerators mentioned above, are preferablyadded to the monomer in amounts of about 0.01% to about 1.0% by weightof the composition prior to forming the dispersion. Othermetallo-containing materials which are non-polymeric have also beenfound to be effective at these levels.

Inhibitors and chelators, well recognized in the art for impartingstability to polymerizable compositions, are recommended. It ispreferred that they be added to the monomer prior to forming thedispersion. Those inhibitors useful in the present composition areusually selected from the group consisting of hydroquinones,benzoquinones, naphthoquinones, phenanthraquinones, anthraquinones, andsubstituted compounds of any of these. Among the chelators which may beoptionally present in the adhesive composition are the beta-diketones,ethylenediamine tetraacetic acid (EDTA) and the sodium salt of EDTA.Both the inhibitors and chelators may be effectively employed in levelsof about 0.1 to about 1% by weight of the monomer, without adverselyaffecting the speed of cure of the polymerizable adhesive composition.

Thickeners, plasticizers, pigments, dyes, diluents, fillers, and otheragents common to the art can be employed in any reasonable manner toproduce desired functional characteristics, providing they do notsignificantly interfere with the monomer polymerization.

The instant adhesive compositions exhibit a marked improvement over theprior art with regard to pot-life, e.g., shelf-life after thefree-radical initiator has been added to the binder and monomerdispersion. The adhesive composition can be kept in this state for daysor weeks without premature polymerization of the adhesive monomers.

Additionally, the preapplied adhesive compositions of the instantinvention have improved resistance to heat aging.

The invention will be more fully understood by the following examples,which are not intended in any way to restrict the effective scope of theinvention.

The preferred method of preparing the instant composition is to slowlymix the binder into deionized water which has been heated to atemperature of about 90° C. The binder is mixed until most of it isdissolved and the batch is clear and free from lumps. The batch iscooled to about 60° C. and the pH adjusted to between about 4 and about6 by addition of NaOH.

The polymeric ferrocene compound is added, followed by 15 minutes ofmixing and the same is done for the inorganic filler. Next the pigmentis mixed in and finally the polymerizable monomer is added and the batchmixed at 25° C. until it is uniform and has the desired dispersionparticle size distribution.

The above method was used for preparation of compositions A, B, and C ofthe examples. Composition D was prepared by methods known in the art forsuch systems (see U.S. Pat. Nos. 3,814,156, and 3,489,599). CompositionsA, B, and C are preferred embodiments of the instant invention.

Table I shows the formulation of the compositions A, B, and C, as wellas that of control composition D, which is a composition using the priorart binder polyvinyl alcohol.

EXAMPLE I

Table II, below, gives the torque values (break/prevail) inpounds-inches of preapplied coatings on a variety of metal nuts andbolts. The bolts were coated manually by rolling them in the adhesivecomposition. The water was then evaporated off. By "break" is meant theforce required to break a bond and cause first motion of the nutrelative to the bolt. By "prevail" is meant the force required to rotatethe nut at the point 180° C. of arc past the point of "break." "Prevail"is thus a measure of the toughness of the cured composition and itsability to resist being ground up in the threads once the nut has beenbroken loose from the bolt.

The instant compositions represented by Compositions A, B, and C showhigher values than Composition D, particularly on inactive surfaces suchas ZN (zinc), CD (cadmium) and treated surfaces such as DM (Dacromet),PS (Polyseal), and ZD (zinc dichromate).

                  TABLE I                                                         ______________________________________                                                    Composition - % by weight                                         Ingredient    A      B        C    D (control)                                ______________________________________                                        H.sub.2 O     47     52       52   57.24                                      EMA-31.sup.1  4.3    3.9      4.2  --                                         EMA-91.sup.2  1.4    1.3      1.4  --                                         PVA.sup.3     --     --       --   3.6                                        Polymeric     0.04   0.03     0.04 0.5                                        Ferrocene cmpd.                                                               Filler        5.8    5.2      5.6  --                                         Pigment       1.4    1.3      1.4  2.33                                       EBPMA.sup.4   40     36       35   36                                         Kelzan.sup.5  --     --       --   0.78                                       ______________________________________                                         .sup.1 Monsanto Co. trade name for linear copolymer ethylene maleic           anhydride.                                                                    .sup.2 Monsanto Co. trade name for crosslinked copolymers of ethylene         maleic anhydride.                                                             .sup.3 Polyvinyl alcohol.                                                     .sup.4 Ethoxylated Bisphenol A dimethacrylate.                                .sup.5 Kelco Co. trade name for a high molecular weight linear                polysaccharide thickener.                                                

                                      TABLE II                                    __________________________________________________________________________    72 Hour Room Temperature Cure - Break/Prevail                                 in inch-pounds on Various Metal Nuts & Bolts                                                                                       P/O Bolt                         P/O  STL  ZN   CD   DM   PS   ZDC  DP   SS   Cu                       __________________________________________________________________________                                                         Nut                      Composition A                                                                         303/300                                                                            131/205                                                                            169/167                                                                            205/179                                                                            232/205                                                                            305/302                                                                            120/187                                                                            252/172                                                                            110/192                                                                            322/207                  Composition B                                                                         274/364                                                                            176/262                                                                            196/130                                                                            174/139                                                                            202/245                                                                            351/360                                                                             92/180                                                                            231/157                                                                            77/172                                                                             --                       Composition C                                                                         292/350                                                                            153/255                                                                            212/132                                                                            214/150                                                                            234/270                                                                            260/240                                                                             95/165                                                                            240/167                                                                            90/170                                                                             --                       Composition D                                                                         220/61                                                                             79/51                                                                              60/20                                                                              102/40                                                                             150/160                                                                            120/60                                                                             75/52                                                                              145/69                                                                             72/175                                                                             --                       (control)                                                                     __________________________________________________________________________     P/O--Phos & oil 3/8 × 16                                                STL--Steel 3/8 × 16                                                     ZN--Zinc 3/8 × 16                                                       CD--Cadmium 3/8 × 16                                                    DM--Dacromet 3/8 × 16                                                   PS--Polyseal 3/8 × 16                                                   ZDC--Zinc dichromate 5/16 × 24                                          DP--Dry Phos M8 × 1.25                                                  SS--Stainless Steel 3/8 × 16                                             P/O Bolt--Phos and oil bolt 3/8 × 16                                   Cu Nut--Copper Nut 3/8 × 16                                        

EXAMPLE II

Tables III, and IV contain hot strength and cyclic heat resistance data,respectively, for each of the compositions tested. Nuts and bolts,coated with preapplied compositions in the manner same as in Example I,were again used as specimens to test break/prevail values. The boltswere coated with preapplied coatings and a nut was wound onto the boltand allowed to cure at room temperature for 72 hours before subjectingthe specimen to temperatures indicated in the tables. Both tables showthe instant invention (A-C) has good resistance to high temperatures,and that it is significantly improved over the polyvinyl alcohol systemon the inactive metal surfaces.

                                      TABLE III                                   __________________________________________________________________________    Hot Strength: 72 Hours, Room temperature cure, 3 Hours at 300°         F.;                                                                           Tested at 300° F.                                                      Break/Prevail, Inch-Pounds                                                            P/O  STL  ZN  CD  DM   PS   ZD   DS                                   __________________________________________________________________________    Composition A                                                                         252/220                                                                             70/202                                                                            82/255                                                                            95/172                                                  Composition B                                                                         195/220                                                                            105/202                                                                            80/137                                                                            67/132                                                  Composition C                                                                         240/255                                                                             97/240                                                                            85/245                                                                            57/180                                                                            162/177                                                                            283/306                                                                            172/105                                                                            67/180                               Composition D                                                                         129/72                                                                             32/37                                                                              45/55                                                                             35/80                                                   (control)                                                                     __________________________________________________________________________

                                      TABLE IV                                    __________________________________________________________________________    Cyclic Heat Resistance                                                        72 Hours Room Temperature Cure; 1 Hour at 300° F.;                     Tested at Room Temperature                                                    Break/Prevail in Inch-pounds                                                          P/O  STL  ZN   CD  DM   PS   ZDC DP                                   __________________________________________________________________________    Composition A                                                                         300/305                                                                             77/322                                                                            135/290                                                                            97/292                                                 Composition B                                                                         382/332                                                                            105/315                                                                             87/316                                                                            82/215                                                 Composition C                                                                         332/407                                                                            102/262                                                                             82/225                                                                            75/260                                                                            190/250                                                                            307/317                                                                            80/242                                                                            275/27                               Composition D                                                                         232/205                                                                            60/40                                                                              65/56                                                                              44/95                                                  (control)                                                                     __________________________________________________________________________

EXAMPLE III

In this example, the intention was to determine if the preappliedcoatings of the instant compositions would remain stable and in theuncured state on metal parts after storage for long periods of time.Tests which accelerate the apparent age of the preapplied coatings wereconducted on bolts having the preapplied coatings by subjecting them toa temperature of 140° C. for 5 days (Table V). The purpose of thesetests was to determine if aging, particularly in warm environments,would result in loss of the composition's strength upon cure, and toinvestigate the possibility of premature polymerization. Each coatedbolt was cooled, mated with a nut, and allowed to cure at roomtemperature for 72 hours. The torque value results on various metal nutsand bolts are reported in Table V. The same procedure was used fortesting the prior art composition D.

A comparison of the break/prevail values for the instant compositions A,B, and C with the prior art composition D shows significant improvementin strength in the instant composition over the prior art.

The effect of high temperature and moisture upon the preapplied coatingwas also tested. Bolts were coated with the compositions indicated inTable VI and subjected for 5 days to an atmosphere of 100% relativehumidity at 100° F. The results are shown in Table VI.

As demonstrated by this example, the instant compositions have shownimprovements over the prior art in the resistance of the former todeterioration upon exposure to heat and moisture and would be expectedto have a high lifetime in the preapplied, uncured state.

                  TABLE V                                                         ______________________________________                                        Heat Aging of Uncured Coated Bolt for 5 days at 140° C.                Bolt was then mated with nut, cured at room temperature                       for 72 hours, and tested at room temperature                                  Break/Prevail in Inch-pounds                                                          P/O     STL      ZN        CD                                         ______________________________________                                        Composition A                                                                           385/392   160/267  262/275 212/323                                  Composition B                                                                           282/315   147/335  210/313 220/247                                  Composition C                                                                           367/397   147/342  215/287 207/270                                  Composition D                                                                           160/65    99/65    71/22   152/67                                   (control)                                                                     ______________________________________                                    

                                      TABLE VI                                    __________________________________________________________________________    Aging of Uncured Coated Bolt for 5 days                                       100% Relative Humidity, 100° F.                                        Test Assembled Nut and Bolt at Room Temperature                               After Room Temperature Cure for 72 Hours                                      Break/Prevail in Inch-pounds                                                          P/O  STL  ZN   CD   DM   PS   ZDC DP                                  __________________________________________________________________________    Composition A                                                                         232/295                                                                            125/272                                                                            127/180                                                                            152/202                                                Composition B                                                                         241/335                                                                            142/315                                                                            150/212                                                                            141/162                                                Composition C                                                                         302/325                                                                            125/207                                                                            155/205                                                                            230/187                                                                            206/176                                                                            225/240                                                                            77/147                                                                            157/130                             Composition D                                                                         225/135                                                                            90/87     167/100                                                                            142/135                                           (control)                                                                     __________________________________________________________________________

Batches of Composition A and B were found to have a pot-life at roomtemperature for more than five weeks without premature cure orsuspension stability problems. However, Composition D, using thepolyvinyl alcohol binder of the prior art, had a pot-life of less than24 hours. Break/Prevail tests on nuts and bolts were conducted oncompositions A and B after the batch was left standing for 3 days. Theresults are tabulated in Table VII, below.

                  TABLE VII                                                       ______________________________________                                        Suspension Stability Test                                                     3 Days, Break/Prevail in inch-pound at room temperature                               P/O     STL      ZN        CD                                         ______________________________________                                        Composition A                                                                           285/325   153/305  212/215 155/90                                   Composition B                                                                           279/288   175/265  212/245 185/105                                  Composition D                                                                           Stability less than 24 hours                                        (control)                                                                     ______________________________________                                    

Table VIII shows a qualitative comparison of the instant invention withvarious other binding systems experimented with during the development.As evidenced by the title, the cure strengths and adhesion capability ofthe applicant's invention is significantly improved over those shown.

                                      TABLE VIII                                  __________________________________________________________________________    Properties of Ethylene Maleic Anhydride Binder                                in Comparison With Other Selected Film Formers                                in The Instant Invention                                                                  Chemical      Cure Strength                                                                            Adhesion                                 Trade Name  Synonyms      24 Hrs. Room Temp.                                                                       to surface                               __________________________________________________________________________    Gantrez Es Resin #225                                                                     Alkyl Monoester of                                                                          40 in. lbs. break                                                                        good                                     GAF Corporation                                                                           Polymethyl vinyl ether                                                                      40 in. lbs. prevail                                 Amphomer Resin                                                                            Acrylic resin 70 in. lbs. break                                                                        poor                                     National Starch           40 in. lbs. prevail                                 Chemical Corp.                                                                Stepanhold R-1                                                                            PVP/ethyl meth-                                                                             150 in. lbs. break                                                                       poor                                     Stepan Chemical. Corp.                                                                    acrylate/methacrylic                                                                        20 in. lbs. prevail                                             acid terpolymer                                                   Combination of PVA.sup.1                                                                  Polyvinyl acetate                                                                           60 in. lbs. break                                                                        good                                     and Rhoplez N619                                                                          acrylic copolymer                                                                           50 in. lbs. prevail                                 Rohm & Haas Co.                                                               Combination of PVA.sup.1                                                                  Polyvinyl acetate                                                                           Low values.sup.2                                                                         poor,                                    and carboset                                                                              acrylic resin            peeling                                  B. F. Goodrich                                                                Ethocel     ethyl cellulose                                                                             Low values on.sup.2                                                                      poor,                                    The Dow Chem. Co.                                                                         resin         zinc surface                                                                             peeling                                  Veegum      Magnesium Aluminum                                                                          Low values on.sup.2                                                                      poor                                     R. T. Vanderbilt Co.                                                                      silicate      steel surface                                                                            peeling                                  Klucel J    Hydroxypropyl Low values.sup.2                                                                         poor,                                    Hercules Inc.                                                                             cellulose                peeling                                  Arolon 557  Acrylic emulsion                                                                            Low values.sup.2                                                                         poor, tacky,                             Ashland Chem.                        peeling                                  EMA-31      Ethylene Maleic                                                                             292 in. lbs. break                                                                       excellent                                EMA-91      anhydride     350 in. lbs. prevail                                Methocell   Methyl cellulose                                                                            Low values.sup.2                                                                         poor,                                    cellulose #1500                                                                           hydroxyethyl cellulose   peeling                                  natrosol 250                                                                              hydroxyethyl ether cellulose                                      Hercules Inc.                                                                 __________________________________________________________________________     .sup.1 Polyvinyl Alcohol                                                      .sup.2 Between 0 to 50 inlbs.                                            

We claim:
 1. An aqueous based adhesive composition, being particularly useful for forming a preapplied adhesive coating or film on parts, especially threaded parts, the composition comprising a dispersion in water of:(a) a polymerizable monomer; (b) a binder at least partly soluble in water; (c) an initiator; and (d) an accelerator of polymerization; wherein the binder is a copolymer of the formula: ##STR5## where Z is selected from the group consisting of: H; C₁₋₁₀ alkyl, alkoxy, alkylene, cycloalkyl; cyano and halo; m is an integer from about 100-1,000; n is greater than 0 but less than 1; and p is 1-n.
 2. An aqueous based adhesive composition comprising a dispersion in water of:(a) a polymerizable monomer; (b) a binder at least partly soluble in water; (c) an initiator; and (d) an accelerator of polymerization, wherein the binder is a copolymer formed by the reaction of an anhydride of the formula: ##STR6## where Z is selected from the group consisting of: H; C₁₋₁₀ alkyl; alkoxy; alkylene; cycloalkyl; cyano; and halo, and a compound selected from the group consisting of arylenes, alkylenes, alkoxylenes, alkarylenes, arylalkylenes, alkoxyalkylenes, alkoxyarylenes, aryloxyalkylenes, and aryloxyarylene.
 3. An adhesive composition according to claim 1 or 2, wherein the polymerizable monomer has the general formula:

    CH.sub.2 ═C(R).COOR.sup.1                              (I)

where R is H, CH₃, C₂ H₅ or Cl, and R¹ is C₁₋₈ mono- or bicycloalkyl, a 3 to 8-membered heterocyclic radical with a maximum of 2 oxygen atoms in the ring, H, alkyl, hydroxyalkyl or aminoalkyl where the alkyl portion is C₁₋₈ straight or branched carbon atom chain.
 4. The adhesive composition of claim 1 or 2, wherein the polymerizable monomer is selected from the class consisting of polyfunctional acrylate and methacrylate esters of polyhydric alcohols, having the general formula: ##STR7## wherein R² is H, C₁₋₄ alkyl or hydroxyalkyl or --CH₂ --OO═C--C(R¹)C═CH₂, R³ is H, halogen or C₁₋₄ akyl, R⁴ is H, OH or --OO═C--C(R¹)═CH₂, m is an integer from 1 to 8, n is an integer from 1 to 20, and p is 0 or 1, R¹ is C₁₋₈ mono- or bicycloalkyl, a 3 to 8-membered heterocyclic radical with a maximum of 2 oxygen atoms in the ring, H, alkyl, hydroxyalkyl or aminoalkyl where the alkyl portion is C₁₋₈ straight or branched carbon atom chain.
 5. The adhesive composition of claim 1 or 2, wherein the polymerizable monomer is selected from the class consisting of acrylate, methacrylate and glycidyl methacrylate esters of Bisphenol-A.
 6. The adhesive composition of claim 5, wherein the monomer is ethoxylated Bisphenol-A-dimethacrylate.
 7. The adhesive composition of claim 1 or 2, wherein the polymerizable monomer is selected from the class consisting of urethane acrylates and substituted acrylate esters having the general formula:

    (CH.sub.2 ═CR.sup.5.CO.O.R.sup.6.O.CO.NH--).sub.2 R.sup.7 (III)

wherein R⁵ is H, CH₃, C₂ H₅ or Cl, R⁶ is (i) a C₁₋₈ hydroxyalkylene or aminoalkylene group, (ii) a C₁₋₆ alkylamino-C₁₋₈ alkylene, a hydroxyphenylene, aminophenylene, hydroxynaphthylene or aminonaphthylene optionally substituted by a C₁₋₃ alkyl, C₁₋₃ alkylamino or di-C₁₋₃ alkylamino group, and R⁷ is C₂₋₂₀ alkylene, alkenylene or cycloalkylene, C₆₋₄₀ arylene, alkarylene, aralkarylene, alkyloxyalkylene or aryloxyarylene optionally substituted by 1-4 halogen atoms or by 1-3 amino or mono- or di-c₁₋₃ alkylamino or C₁₋₃ alkoxy groups; or said acrylates having the general formula:

    (CH.sub.2 ═CR.sup.5.CO.O.R.sup.6.O.CO.NH.R.sup.7.NH.CO.X--).sub.n R.sup.8                                                   (IV)

wherein R⁵, R⁶, and R⁷ have the meanings given above, R⁸ is the non-functional residue of a polyamine or a polyhydric alcohol having at least n primary or secondary amino or hydroxy groups respectively, X is O or NR⁹ where R⁹ is H or a C₁₋₇ alkyl group, and n is an integer from 2 to
 20. 8. The adhesive composition of claim 3, wherein the polymerizable monomer is hydroxypropyl methacrylate or 2-hydroxyethyl methacrylate.
 9. The adhesive composition of claim 3, wherein the polymerizable monomer is selected from the class consisting of acrylic acid, methyl methacrylate, tetrahydrofurfuryl methacrylate, cyclohexyl methacrylate, and 2-aminopropyl methacrylate.
 10. The adhesive composition of claim 6, wherein the pH is about 2 to about
 12. 11. The adhesive composition of claim 1 or 2, wherein the initiator is a free-radical initiator and is present in the amounts of about 0.1% to about 10% by weight of the monomer and is selected from the group consisting of peroxides, peresters, and peracids.
 12. The adhesive composition of claim 11, wherein the free-radical initiator is benzoyl peroxide and is present in the amount of about 0.1 to about 2% by weight of the monomer.
 13. The adhesive composition of claim 1 or 2, wherein the accelerator of polymerization is selected from the group consisting of amines, sulfimides, aldehyde-amine condensation products, non-polymeric ferrocene compounds, and polymeric ferrocene compounds.
 14. The adhesive composition of claim 13 wherein the amine is N,N-dimethylparatoluidine, the sulfimide is saccharin, and the aldehyde-amine condensation product is butyraldehydeaniline.
 15. The composition of claim 14, wherein there is included a dye or fluorescent pigment.
 16. The adhesive composition of claim 15, wherein the composition contains an inhibitor in the amount of about 0.1% to about 1% by weight of the monomer, selected from the group consisting of hydroquinones, benzoquinones, naphthaquinones, phenanthraquinones, anthraquinones, and a substituted compound of any of the foregoing.
 17. An article, coated with a film formed by evaporation of water from an adhesive composition, said composition comprising a dispersion in water of:(a) a polymerizable monomer; (b) a binder at least partly soluble in water; (c) an initiator; and (d) an accelerator of polymerization, wherein the binder is a copolymer of the formula: ##STR8## where Z is H, C₁₋₁₀ alkyl, alkoxy, alkylene, cycloalkyl; cyano, halo; m is an integer from about 100-1,000; n is greater than 0 but less than 1; and p is 1-n.
 18. The article of claim 17, wherein the adhesive composition is a dispersion in water of:(a) a polymerizable monomer; (b) a binder at least partly soluble in water; (c) an initiator; (d) an accelerator of polymerization selected from N,N-dimethylparatoluidine, saccharin and butyraldehyde-aniline condensation product; (e) a dye or fluorescent pigment; and (f) an inhibitor in the amount of about 0.1% to about 1% by weight, selected from the group consisting of hydroquinones, benzoquinones, naphthaquinones, phenanthraquinones, anthraquinones, and a substituted compound of any of the foregoing,wherein the binder is a copolymer of the formula: ##STR9## where Z is selected from the group consisting of: H, C₁₋₁₀ alkyl, alkoxy, alkylene, cycloalkyl, cyano, and halo; m is an integer from about 100-1,000; n is greater than 0 but less than 1; and p is 1-n.
 19. The article of claim 18, wherein the article is a threaded fastener.
 20. The article of claim 19, wherein the adhesive composition additionally contains a chelator in the amount of about 0.1 to about 1% by weight of the monomer.
 21. The adhesive composition of claim 16, wherein the composition additionally contains a chelator in the amount of about 0.1 to about 1% by weight of the monomer.
 22. The adhesive composition of claim 10, wherein the pH is about 4 to about
 6. 